The plant is still mostly owned by NSP/Xcel, although Southern Minnesota Municipal Power Agency has a 41 percent stake in the 876-MW Unit 3, which was built from 1983 to 1987 at a cost of about $1 billion.

[10] The incident occurred during a test cycle following an upgrade to the steam turbine where it was intentionally spun up beyond 3,600 rpm to check that safety mechanisms functioned properly.

One cylindrical piece of the exciter the size of a five-gallon (19 liter) bucket landed next to the control room door and was still spinning at sufficient speed to drill a divot into the floor.

[11] Prior to this filing, Xcel had planned to reduce its carbon dioxide emissions across the Upper Midwest by 40% by the year 2030 (from 2005 levels), but closing both of these units will contribute to a new goal of a 60% reduction in the same time frame.

[11] Initial notes made by the PUC indicate a desire to instead cease operations at the nearby Monticello Nuclear Generating Plant as a reduction in total carbon emissions would come at a greater cost to the rate paying customers in the state of Minnesota.

[13] Recent conclusions drawn from Xcel Energy's ongoing rate case with the PUC found that the Monticello plant would cost the customers significantly more than expected.

[14] As a result the PUC has redirected efforts away from ceasing operations at Sherco and the plant is expected to stay open for longer than initially anticipated in order to reduce the impact on low cost electricity supply in the state.

[18] It was reported in April 2021 that Xcel will bring a 460 megawatt solar plant online at the site by 2024, the same date as the expected shutdown of one of the coal units, according to the Star Tribune.